Contents

Regulation

The regulation of appetite has been the subject of much research. Breakthroughs included the discovery, in 1994, of leptin, a hormone that appeared to provide negative feedback. Later studies showed that appetite regulation is an immensely complex process involving the gastrointestinal tract, many hormones, and both the central and autonomic nervous systems.

Role in disease

A limited or excessive appetite is not necessarily pathological. Abnormal appetite could be defined as eating habits causing malnutrition on the one side or obesity and its related problems on the other.

Both genetic and environmental factors may regulate appetite, and abnormalities in either may lead to abnormal appetite. Poor appetite (anorexia) may have numerous causes, but may be a result of physical (infectious, autoimmune or malignant disease) or psychological (stress, mental disorders) factors. Likewise, hyperphagia (excessive eating) may be a result of hormonal imbalances, mental disorders (e.g. depression) and others.

Various hereditary forms of obesity have been traced to defects in hypothalamic signalling (such as the leptin receptor and the MC-4 receptor), or are still awaiting characterisation (Prader-Willi syndrome).